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Robot-capsule anchoring: An initial prototype of the robot-capsule anchors inside a transparent tube, mimicking the way that it would stick in the esophagus.
Credit: Metin Sitti, Carnegie Mellon University

A swallowable robot can be stuck and unstuck to a spot on command

By Kristina Grifantini, August 4, 2008, MIT Technology Review – For the past few years, medical researchers have been trying to develop ways to peer painlessly inside the human body, from a swallowable sensor to a magnetically controlled image-snapping capsule. Now, a group at Carnegie Mellon University (CMU) has shown that a tiny capsule robot is adhesive enough to anchor inside an intestine and yet gentle enough not to tear soft tissue.

The anchoring robot would be swallowed like a normal pill and move through the body until it reached the gut. Then a doctor, using a wireless control, would tell the robot when to expand its legs and anchor. It would be good not only for snapping images, but also potentially for biopsies, drug delivery, heat treatment, and other treatment applications.

While doctors have, for the past several years, used a camera pill that transmits images of the intestines, being able to control the movement of such a device would have many benefits, says Mark Schattner, a gastroenterologist at the Memorial Sloan-Kettering Cancer Center, who was not involved in the work. “The number-one use would be biopsy,” says Schattner. “The other would be control of bleeding–if you could cauterize or laser a source of bleeding, that would be [a] major therapeutic use.” While the CMU robot is not yet ready for such uses, its ability to securely and safely anchor in the body is the first step in achieving more-advanced applications.

The trick to making the robot was finding an adhesive that would “stick repeatedly to tissues like intestines, esophagus, stomach, heart, and kidney surfaces,” says Metin Sitti, a professor and principal investigator of the NanoRobotics Lab at CMU. Although strong biomedical adhesives exist, they stick once and cannot be removed. Other attempts to create removable adhesives utilized clamps and hooks, which could potentially damage tissue. By developing a strong adhesive that can attach and reattach many times, Sitti hopes to build a robot that can actually crawl inside the human body for therapeutic purposes without causing harm.

Sitti and his lab group looked to beetles, which secrete oil-like liquids along their foot hairs in order to stick securely to surfaces. They coated their robot’s feet with a similarly viscous liquid to “help get more adhesion by giving them a surface-tension component,” says Sitti. Aside from increasing capillary and intermolecular forces, secretions help feet adhere to rough surfaces by filling in the gaps, he adds.

The group attached three robotic legs to a standard capsule camera and covered microscopic fibers on the adhesion pads with biocompatible silicone oil. The capsule robot is one centimeter in diameter and three centimeters in length, with 1.5-centimeter-long feet that open on demand and press into the surface of the tissue to increase friction and anchor the device, says Sitti. In a recent paper published in the Journal of Adhesion Science and Technology, Sitti showed that the oil increased adhesion up to 25 percent over a dry attempt on a smooth surface. On a slightly rough surface, the oily layer improved adhesion by almost 6 times. Recently, the team demonstrated that the capsule robot can successfully anchor on animal intestines in vitro, says Sitti, as well as on an animal esophagus.

“Clearly, a capsule that you can control in real time is going to be the next major advance for capsule-based systems,” says Schattner. “The current capsule technology is not controllable: you’re at the mercy of what the body is doing. The only thing you can do is image. You can’t do anything therapeutic.” Doctors have used the capsules to image the esophagus, colon, and–mainly–small intestine.

Sitti’s group is also mimicking gecko feet. Geckos have angled hairs on their feet that allow them to pull in one direction to adhere more securely, and in another direction to detach. “We made some angled fibers [where] in one direction friction is very high, and the other direction it’s low,” says Sitti. The group plans to put the angled fibers on the capsule robot in the future.

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Taking a few precautionary steps can help Americans visiting China for the 2008 Olympic Games go for the gold by avoiding health woes associated with international travel, according to Joint Commission International (JCI). JCI is the international arm of The Joint Commission, and accredits more than 170 hospitals worldwide.

“The adage that an ounce of prevention is worth a pound of cure is a good one to remember any time you’re traveling abroad,” says Karen H. Timmons, CEO, JCI. “By thinking ahead about potential health care needs and treatment options overseas, Americans can stay healthy and enjoy the Games.”

Before leaving for the August 8-24 Olympics, it is important that patients speak with their doctor about the trip and about any specific health risks related to their medical history. This is especially important if a patient has a known condition. Travelers should also review their vaccination history to be sure they are up-to-date on routine shots such as measles/mumps/rubella (MMR), tetanus, polio, and meningitis. For patients over age 50, a flu shot may also be in order. Although there are no immunizations required to visit China, the Centers for Disease Control and Prevention (CDC) recommends vaccinations against hepatitis A, hepatitis B, typhoid and rabies.

Other tips for patients from JCI that can make the difference between a health victory or defeat at the 2008 Games:

— Order double your prescription medications to keep one in carry-on luggage and the other in checked luggage. Keep medications in their regular containers, if possible, and bring the prescription or a doctor’s note.

— Beware of traveler’s diarrhea. A good rule for travelers is: Eat it only if you can cook it, boil it or peel it. If not, then avoid it. It’s also important to drink bottled water only and make sure that milk products are pasteurized. If you get traveler’s diarrhea, avoid dairy products and alcohol.

— Bring important medical documents with you. This includes your health insurance card, a brief history of any chronic conditions such as diabetes, or past treatment for specific conditions or illnesses.

— Make sure you’re aware of your existing travel insurance travel policies, and bring copies of the policy with you. Travelers may also want to consider purchasing a supplemental policy for medical evacuations.

— If you require medical care, find a JCI accredited facility. Beijing United Family Hospital is accredited by JCI and is near the Olympic venue. The address is #2 Jiangtai Lu, Chaoyang District, Beijing 100016 PR China. To contact the hospital, call +86(10) 5927 7000 or +86(10) 5927-7120 for emergencies, or visit www.unitedfamilyhospitals.com/en_index.asp.

— Contact the hotel concierge, travel tour operator or U.S. Embassy if you need immediate help.